Short answers, pulled from the story.
The word monarch first appeared in the mid-15th century as monark, meaning a supreme governor for life. It comes from the Old French monarche of the 14th century and directly from the Late Latin monarcha. This term derives from the Greek monarkhēs, which means one who rules alone.
After reaching a peak in the middle of the 19th century, the proportion of monarchies in the world has steadily declined. Republics replaced many monarchies notably at the end of World War I and World War II. A 2020 study suggests monarchy arose as an efficient system for governing large populations when coordination was difficult but became less efficient later due to innovations in communications and transportation technology.
There are approximately twelve absolute monarchies governed as autocracies. Nations such as Morocco, Qatar, Liechtenstein, and Thailand feature hereditary monarchs with more political influence than any other single source of authority. Brunei, Oman, and Saudi Arabia are also classified as absolute monarchies within the Muslim world.
Sweden became the first monarchy to declare equal full cognatic primogeniture in 1980 meaning the eldest child whether female or male ascends to the throne. Other kingdoms like the Netherlands in 1983 and Norway in 1990 followed suit. The United Kingdom adopted absolute equal primogeniture on the 25th of April 2013 following agreement by prime ministers of sixteen Commonwealth Realms.
Japan has had an emperor according to legend since Emperor Jimmu who reigned from 660 to 585 BCE making it the world's oldest existing monarchy. Currently forty-three sovereign nations in the world have a monarch including fifteen Commonwealth realms that share King Charles III as their head of state. European constitutional monarchies include Belgium, Denmark, Luxembourg, the Netherlands, Norway, Spain, and Sweden.